(1) Field covered by the invention
The present invention relates to a method and a system for the adjustment of a specimen supported by a specimen support able to be changed over from one clutch state to another, the specimen being on a specimen table of an electron microscope or other corpuscular beam apparatus, adjustment of the specimen table normal to a longitudinal axis of the apparatus being possible in two coordinate directions.
(2) The prior art
German Pat. No. 2,236,530 describes a specimen adjustment system for a corpuscular beam apparatus, as an electron microscope, which has a longitudinal apparatus axis, a specimen table and a tilting unit. The specimen table serves for adjusting a specimen support or mount, placed on it, in two directions normal to the apparatus axis, while the tilting system is used for tilting the table or the specimen support, placed on it, about a tilt axis essentially normal to the apparatus axis. The specimen table and the tilting unit are mechanically separated and the specimen support can be selectively coupled with the specimen table or the tilting unit. The specimen support is first coupled with the specimen table and then a desired part of the specimen is put into the desired position by moving the specimen table to which the specimen support is coupled, in relation to the apparatus axis. After this has been done, the specimen is coupled with the tilting unit, which may form a part of a microgoniometer. The specimen adjustment unit then makes possible an "eccentrical" positioning adjustment of the specimen, that is to say placing the specimen in the point of intersection of the tilting axis and a turning axis of the goniometer, which, in the zero position of the tilting system, generally coincides with the apparatus axis.
In the case of this known specimen adjustment system the joining of the specimen support with the specimen table or the tilting system is mechanical and may be selectively activated by a clutch. It has been suggested, however, that a clutch system of the above discussed general type be made wherein the coupling is performed by electrical force making use of the Johnsen-Rahbek effect (see "Electron Microscopy 1974, Abstracts of papers presented to the Eighth International Congress on Electron Microscopy, Canberra, 25th to 31st August 1974", publisher:
The Australian Academy of Science Canberra, A.C.T. Australia, Vol. I, pages 194 and 195).
In accordance with another earlier suggestion, a tilting and turning system, which are generally designed together in the form of a goniometer rod, of a goniometer ("tilt-turn goniometer") was to be bearinged in a frame, which may undergo adjustment into two coordinate directions (X and Y) normal to the apparatus axis and, generally speaking, furthermore parallel to the apparatus axis. This frame, moved in the X and Y directions, takes the form of a second or "operation" specimen table, which is present in addition to the firstly-noted "adjustment" specimen table.
Lastly, there has been another earlier suggestion to have, in place of the turning unit, a second tilting unit, whose axis is normal to the axis of the first tilting unit (rod axis) and to the apparatus axis. With such a goniometer design for two forms of tilt, the specimen may be lined up, in any possible way desired, with respect to the apparatus axis, on the same lines as in a turn-tilt goniometer.